114 DISCOVERY REPORTS 



Acodontaster waitei also has these pedicellariae and so closely resembles conspicmis in 

 most respects that the two forms may easily be confused. Whether they are 2 species, or 

 forms of one, will require more material to determine. A. conspicmis is characterized by 

 a large unpaired tooth with a well-developed hyaline tip ; while in waitei the unpaired 

 tooth is inconspicuous, compressed, the hyaline point only slightly or not at all apparent. 



It seems to me to be probable that the two specimens (G, H) which Koehler names 

 variety inarmata (1920, p. 210, pi. 43, figs. 6, 7) may well be the young of some forma of 

 A. e long of us. 



Acodontaster elongatus var. abbreviatus Koehler, from Cumberland Bay, South 

 Georgia, 24-52 m., was based upon a single immature specimen (R 22 mm.), in which 

 the rays are relatively shorter than in the adult. Pedicellariae characteristic of A. 

 conspicuus are present on the abactinal, superomarginal, and inferomarginal plates, while 

 there is a conical fasciculate pedicellaria, composed of 4 spines, at the oral angle of each 

 actinal area. A specimen with R 36 mm. from St. 42 has an identical distribution of the 

 same kinds of pedicellariae, there being 2 or 3 fasciculate pedicellariae near the oral 

 angle. Their valves are about twice as broad as the adjacent spines. As the animal grows 

 the valves of all the pedicellariae increase in breadth more rapidly than do the surround- 

 ing granules, so that they are relatively larger in old specimens. 



Type locality. St. i (Australasian Antarctic Exp.) 66° 50' S, 142° 06' E, 354 

 fathoms. 



Distribution. Off AdeHe Land, 25-354 fathoms; off Graham Land, 150 m.; 

 South Georgia, 24-250 m. If the specimen from St. WS 865 is correctly labelled, 

 Falkland Plateau is the northern limit. 



Acodontaster waitei (Koehler) 



Metadontaster waitei Koehler, 1920, p. 219, pi. 46, figs. 1-6; pi. 47, figs. 5, 6; pi. 48, fig. 8; pi. 49, 

 figs. 1-3, 19; pi. 71, figs. I, 2. 

 St. 181. SchoUaert Channel, Palmer Archipelago, 64° 20' S, 63° 01' W, 160-335 m., mud, 

 I specimen (R 75 mm., r 29 mm.). 



This is probably a form of A. conspicmis, which it closely resembles in all characters 

 except that of the specialized oral spine and in having spinose conical fasciculate pedi- 

 cellariae on the first few adambulacral plates. The tooth is smaller, and narrower at the 

 base, than in conspicmis. It is compressed, and instead of lying close along the median 

 oral suture, stands erect. The tip is covered by the integument or else only a very small 

 hyaline portion protrudes. The actinal pedicellariae are in no wise different from those of 

 conspicmis, as may be seen from Koehler's figure (1920, pi. 46, fig. 2) ; but they are more 

 numerous in our example since the series adjacent to the adambulacral plate extends for 

 a third to half the length of the furrow (10-20 pedicellariae). In addition, smaller 

 pedicellariae occur on the proximal inferomarginal plates (absent in Koehler's specimens) 

 but there are none on the abactinal surface. These inferomarginal pedicellariae are 

 identical in form with those of conspicuus. 



